1. Field of the Invention
The present invention relates to a facsimile apparatus that communicates based on Recommendations V. 8 and V. 34 formulated by the ITU-T (Telecommunication Standardization Sector of International Telecommunication Union).
2. Related Background Art
The V. 8 and V. 34 procedures were recommended by the ITU in September 1994. See, Data Communication Over The Telephone Network, Procedures For Starting Sessions Of Data Transmission Over The General Switched Telephone Network, ITU-T Recommendation V.8, and Data Communication Over The Telephone Network, A Modem Operating At Data Signalling Rates Of Up To 28800 bit/s For Use On The General Switched Telephone Network And On Leased Point-To Point 2-Wire Telephone-Type Circuits, ITU-T Recommendation V.34, both of which are incorporated herein by reference.
In these V. 8 and V. 34 procedures, communications are full-duplex. Image transmission according to the V. 34 procedure requires a higher S/N ratio and a wider band width than conventional facsimile apparatuses that meet with the V. 17 Recommendation.
For this reason, communication errors are expected to occur more frequently in the V. 8 procedure, V. 34 procedure and V. 34 image transmission than in the V. 21 procedure, and V. 27 ter., V. 29 and V. 17 image transmissions.
When a communication error takes place during V. 8 and V. 34 communication, a transmitter side performs redialing, and a receiver side attempts to communicate through V. 8 and V. 34 procedures. In this case, a communication error is likely to occur again unless the line characteristics involved are changed. Before completing the communication, a line is continuously occupied for a long period of time and the cost for communication is pushed up.
If a retransmission is made subsequent to a communication error using the conventional method, the communication time is prolonged without fully exploiting the high-speed characteristic of V. 34 image transmission.